1. Field of the Invention
The present invention relates to an image forming apparatus including a rotating member adapted to support an image and a transmission mechanism that transmits a drive force generated by a drive source to the rotating member.
2. Description of Related Art
An image forming apparatus as mentioned above is disclosed in Japanese Patent Laid-Open Publication No. 2010-102247, for example. In Japanese Patent Laid-Open Publication No. 2010-102247, the transmission mechanism includes a drum drive gear, a coupling disc, an encoder head, and a control circuit.
The drum drive gear is positioned coaxially with a rotating shaft of a photoreceptor drum, which is an example of the rotating member. The coupling disc engages with the photoreceptor drum and the drum drive gear. The encoder head detects information about the rotation of the coupling disc. The control circuit controls the rotation of the photoreceptor drum on the basis of the rotation information detected by the encoder head.
Here, the drum drive gear and the coupling disc engage with each other via a viscoelastic member. By passive vibration control using the viscoelastic member, a resonant frequency of the photoreceptor drum or the like is shifted from original value, thereby reducing transmissibility of input vibrations having the certain frequency.
However, such passive vibration control simply shifts the resonant frequencies, so that resonance characteristics of other frequency bands (e.g., a low-frequency band) persist. The persistence of the resonance characteristics causes a problem where conventional drive force transmission mechanisms cannot suppress the vibration of the photoreceptor drum (i.e., the rotating member) upon input of vibration that is difficult to predict.